DE-crypting calls

Florian Rebstock florian.rebstock at
Wed May 21 16:09:07 CEST 2008

joerg at schrieb:
> Am Fr  16. Mai 2008 schrieb Al Johnson:
>> On Friday 16 May 2008, ramsesoriginal wrote:
>>> I was just wondering: we have seen the problems of encryptingcalls.
>>> But what about decrypting them? Let*s say someone hasa method to call
>>> you with some sort of encryption.. would it be possible to write a
>>> decryption for it? Maybe public key?
>> Depends what sort of calls you mean. If it's GSM voice calls then the same 
>> problems apply as already discussed. If you're talking about a data link 
>> encrypted end to end and passing voice data then it's possible, probably 
>> using established standards. You could make an OpenVPN or IPsec tunnel end 
> to 
>> end, then use SIP, h323 or IAX2 over it. You could use one of the secured 
>> versions of SIP directly, at least one of which uses public keys, but none 
> of 
>> them are universally accepted. 
> What about ZRTP? (Zimmerman, PGP inventor). Have a look at! Via 
> GSM you can setup not only voice calls, but also fax and *DATA* calls with up 
> to 14400bps. Tunneling SIP and low bandwidth RTP/ZRTP through this link 
> should be feasible with low effort
maybe someone is able to port ekiga and zfone to the FR?
So we can talk secure with a internetconnection over Bluetooth or Wlan.

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